CHARACTERIZATION OF THE TRANSPORT PROCESSES IN FE-CR-NI STAINLESS-STEEL

Measurements of electrical resistivity, X-ray diffraction and DTA were used to characterize the transport processes developed in an Fe-12.1 Cr-7.37 Ni (wt. %) stainless steel during heating from 300 to 980 K an d subsequently during cooling to room temperature. The results reveale d that this steel exhibits two transport regions during heating and on ly one during cooling. In case of heating, the first transition region (observed in the temperature range 650-730 K) is not to a structural but may be a magnetic transition. The second transition region (observ ed in the temperature range 885-915 Kj is ascribed to the austenitic s tructural transformation. During cooling, a unique transition region w as observed in the range 560-434 K. This was attributed to the martens itic transformation which may also be associated with a magnetic trans ition. From the DTA data, the effective activation energy for the aust enitic transformation was determined to be 459.3 kJ mol(-1). In the te mperature ranges other than the transition regions the electrical resi stivity fits a linear equation rather than the Bloch-Gruneisen equatio n. (C) 1997 Elsevier Science S.A.